<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <meta http-equiv="X-UA-Compatible" content="ie=edge" />
    <title>animation</title>
    <style>
      #one {
        width: 50px;
        height: 50px;
        background-color: orange;
        animation: run;
        animation-delay: 0.5s;
        animation-duration: 2s;
        animation-fill-mode: forwards;
      }

      @keyframes run {
        0% {
          width: 100px;
        }
        50% {
          width: 400px;
          background-color: blue;
        }
        100% {
          width: 800px;
        }
      }
    </style>
  </head>
  <body>
    <div id="one"></div>
  </body>
</html>
